Single carbon nanotube transistor at GHz frequency

We report on microwave operation of top-gated single carbon nanotube transistors. From transmission measurements in the 0.1-1.6 GHz range, we deduce device transconductance g(m) and gate-nanotube capacitance C-g of micro- and nanometric devices. A large and frequency-independent g(m) similar to 20 16 is observed on short devices, which meets the best dc results. The capacitance per unit gate length of 66 aF/mu m is typical of top gates on a conventional oxide with epsilon similar to 10. This value is a factor of 3-5 below the nanotube quantum capacitance which, according to recent simulations, favors high transit frequencies f(T) = g(m)/2 pi C-g. For our smallest devices, we find a large f(T) similar to.50 GHz with no evidence of saturation in length dependence,